CN110237713B

CN110237713B - Electric response polymer film and preparation method, use method and application thereof

Info

Publication number: CN110237713B
Application number: CN201910598326.1A
Authority: CN
Inventors: 胡承志; 谭笑; 曲久辉; 孙境求; 赵凯; 马百文; 戚菁
Original assignee: Research Center for Eco Environmental Sciences of CAS
Current assignee: Research Center for Eco Environmental Sciences of CAS
Priority date: 2019-07-04
Filing date: 2019-07-04
Publication date: 2021-04-09
Anticipated expiration: 2039-07-04
Also published as: CN110237713A

Abstract

The invention relates to an electric response polymer film and a preparation method, a using method and application thereof, wherein the electric response polymer film comprises a porous polymer film matrix and a polypyrrole film covering the pore wall and the surface of the porous polymer film matrix, and the polypyrrole film is doped with large-volume anions; the bulky anion comprises any one or at least two of alkyl benzene sulfonate ion, alkyl sulfate ion and dioctyl succinate sulfonate ion; the alkyl is C7-C12 alkyl. The electric response polymer membrane has the function of membrane pore expansion, can realize the removal of membrane pollutants and the selective interception of organic pollutants, and has good mechanical property and stability.

Description

Electric response polymer film and preparation method, use method and application thereof

Technical Field

The invention relates to the technical field of water treatment, in particular to an electric response polymer film and a preparation method, a use method and application thereof.

Background

The membrane separation technology is widely applied to the field of water treatment, but the membrane pollution is caused because pollutants are easy to accumulate on the surface of the membrane and block membrane pores, the service life of the membrane is greatly reduced, and the application of the membrane technology is seriously hindered. Generally, the performance of the traditional membrane material is difficult to be autonomously adjusted through external stimulation, and intelligent control is not easy to realize. In recent years, much research has focused on developing conductive films with controlled properties to mitigate membrane fouling and improve selective separations.

CN107441945A discloses a method for preparing a water treatment filter membrane, which comprises the steps of preparing a hollow fiber membrane, preparing a CMC solution and performing compression molding to complete the preparation of the water treatment filter membrane; through the arrangement of a specific process, the water treatment filter membrane obtained by production has good removal rate on sodium chloride and magnesium sulfate and good water yield, can realize continuous industrial production, has uniform and stable nanofiltration functional layer, and has wide application prospect in the fields of seawater and brackish water desalination, sewage treatment and ultrapure water preparation. However, after the water treatment membrane is used for a long time, the membrane pores are easy to block, and the service life is short.

CN109569333A discloses a composite membrane for water treatment, which is prepared by mixing sepiolite, polysulfone and surfactant treated by coupling agent as membrane-making raw materials with solvent in a certain proportion to prepare membrane casting solution, preparing a porous support membrane by an immersion-precipitation method, and coating a separation functional layer on the porous support membrane by chemical deposition reaction of polyphenol and polyamino compound in water. The membrane exhibits high retention of dyes and inorganic salts. Also, the membrane pores of the composite membrane are clogged and difficult to clean.

CN109647230A discloses a preparation process of a PTFE (polytetrafluoroethylene) foamed plate water treatment membrane, which comprises the following steps: (1) adding a presintered PTFE suspension into a bin of a pressing container; (2) controlling the pressing strokes of an upper pressing plate and a lower pressing plate of the pressing container according to the volume of a bin of the pressing container and the required apparent density of the pre-sintered PTFE suspension; (3) after the presintered PTFE suspension material in the storage bin is pressed to the required apparent density, maintaining the pressure to form a workpiece; (4) placing the workpiece into a drying oven for sintering to form a prefabricated part; (5) and placing the prefabricated member on a rotary cutter for rotary cutting to form the PTFE foamed plate. The water treatment membrane has the characteristics of easy manufacture, high strength and good environmental protection. But removal of membrane contaminants and selective entrapment of organic contaminants is difficult to achieve.

Therefore, there is a need in the art to develop a novel water treatment membrane, which can simultaneously achieve the removal of membrane contaminants and the selective interception of organic contaminants, and has good mechanical properties and stability.

Disclosure of Invention

One of the objectives of the present invention is to provide an electric response polymer membrane, which has the function of membrane pore expansion and contraction, can realize the removal of membrane pollutants and the selective interception of organic pollutants, and has good mechanical properties and stability.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides an electric response polymer film, which comprises a porous polymer film matrix and a polypyrrole film, wherein the polypyrrole film covers the pore wall and the surface of the porous polymer film matrix, and large-volume anions are doped in the polypyrrole film;

the bulky anion comprises any one or at least two of alkyl benzene sulfonate ion, alkyl sulfate ion and dioctyl succinate sulfonate ion;

the alkyl group is C7-C12 (e.g., C8, C9, C10, C11, etc.).

The polypyrrole film is doped with the large-volume anions, the current carrier is a necessary condition for material conduction by utilizing an electric effect of ion embedding/de-embedding, the current carrier does directional motion under a certain electric field to form current, when an oxidation potential is applied, the doped large-volume anions do not move, the cations are exchanged into a solution, the distance between chains in the polypyrrole is shortened, the size of the polypyrrole film is reduced, and the pore of the polypyrrole film is enlarged; when reduction potential is applied, anions are fixed in the polymer due to large volume, in order to keep charge balance, cations in the solution can enter the polymer, the volume of polypyrrole expands, the volume of polypyrrole increases, and membrane pores decrease, so that the pore size of the electric response polymer membrane can be dynamically adjusted through electrode potential, membrane pollution can be effectively controlled through backwashing when membrane pores increase, and selective interception of organic pollutants can be realized when membrane pores decrease.

Preferably, the thickness of the porous polymer membrane matrix is 200-400 μm, such as 210 μm, 220 μm, 230 μm, 240 μm, 250 μm, 280 μm, 300 μm, 350 μm, 380 μm, etc., preferably 200 μm.

Preferably, the thickness of the polypyrrole film is 5% to 10%, such as 6%, 7%, 8%, 9%, etc., of the thickness of the porous polymer film matrix.

The present invention prefers a specific thickness of the polypyrrole film, at which the polymer film has better conductivity, too large thickness, which results in incomplete deposition of polypyrrole in the base film and prolonged polymerization time, and too small thickness, which results in unforgeable film and poor mechanical properties.

Preferably, the polymer in the porous polymer membrane matrix comprises any one of polyvinylidene fluoride, polyethersulfone, cellulose acetate and polyamide, preferably polyvinylidene fluoride.

Preferably, the polypyrrole is polymerized from pyrrole in a molar ratio of bulky anion to pyrrole of 0.005 to 0.01:1, e.g., 0.006:1, 0.007:1, 0.008:1, 0.009:1, etc., preferably 0.007: 1.

The invention preferably selects the doping proportion, the polypyrrole film obtained in the proportion range has better conductivity, the doping degree of the polypyrrole is generally between 0.25 and 0.33, on average, every three or four pyrroles have a monovalent bulky anion, and the stability of the doping structure is good. Too little bulky anion doping results in lower conductivity and reduced thermal stability.

Preferably, the polypyrrole is prepared by gas phase polymerization of pyrrole.

Through gas phase polymerization, the polypyrrole film can uniformly cover the surface and the pore diameter of the substrate, and the conductivity of the polypyrrole film can be improved.

Preferably, the gas phase polymerization temperature is 12-25 ℃, such as 13 ℃, 14 ℃, 15 ℃, 16 ℃, 17 ℃, 18 ℃, 19 ℃, 20 ℃, 21 ℃, 22 ℃, 23 ℃, 24 ℃, preferably 15 ℃.

The invention preferably utilizes a gas-phase polymerization method to synthesize the electric response polymer film with the telescopic film hole, is easy to synthesize and low in cost, and the obtained polypyrrole film layer is uniform and compact, is beneficial to improving the conductivity and is not easy to generate secondary pollution.

Preferably, the gas phase polymerization time is 2 to 8h, such as 2.3h, 3.2h, 3.3h, 3.4h, 3.5h, 3.6h, 3.7h, 3.8h, 3.9h, 4h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, etc., preferably 4 h.

In the invention, the gas-phase polymerization time is preferably matched with the gas-phase polymerization temperature, so that the obtained polypyrrole film has better compactness and conductivity.

Preferably, the alkylbenzene sulfonate ion is dodecylbenzene sulfonate ion.

Preferably, the alkyl sulfate ion is dodecyl sulfate ion.

Preferably, the alkyl sulfonate ion is dodecyl sulfonate ion.

Preferably, the bulky anion comprises an alkylbenzene sulfonate ion.

According to the invention, the preferable large-volume anions comprise alkyl benzene sulfonate ions, and the doped heterocyclic aromatic groups in the polypyrrole have a stabilizing effect on carriers of the polymer, so that the number of the carriers in the polypyrrole film is increased, the conductive capability of the polypyrrole film is greatly improved, and in addition, the doped alkyl benzene sulfonate ions can effectively improve the mechanical property of the polypyrrole film and improve the stability of the polypyrrole.

Preferably, the average pore diameter of the electrically responsive polymer film when subjected to an oxidation potential is 70-82nm, such as 71nm, 72nm, 73nm, 74nm, 75nm, 76nm, 77nm, 78nm, 79nm, 80nm, 81nm, etc., preferably 82 nm.

Preferably, the average pore diameter of the electrically responsive polymer film when the reduction potential is applied is 65 to 75nm, such as 66nm, 67nm, 68nm, 69nm, 70nm, 71nm, 72nm, 73nm, 74nm, etc., preferably 70 nm.

Another object of the present invention is to provide a method for producing an electrically responsive polymer film according to the first object, the method comprising the steps of:

(1) preparing a porous polymer membrane substrate by adopting a phase inversion method;

(2) placing the porous polymer film matrix in a mixed solution of bulky anion salt and pyrrole, and forming a polypyrrole film doped with bulky anions on the pore wall and the surface of the porous polymer film matrix through a polymerization reaction to obtain the electric response polymer film;

the bulky anion comprises any one or at least two of alkyl benzene sulfonate, alkyl sulfate and dioctyl dibutyrate sulfonate;

the alkyl is C7-C12 alkyl.

Preferably, step (1) specifically comprises: dissolving a pore-forming agent in a solvent, stirring for the first time to obtain a pore-forming agent solution, adding a polymer into the pore-forming agent solution, stirring for the second time to obtain a mixed membrane casting solution, coating the mixed membrane casting solution on a glass plate, and stripping to obtain a porous polymer membrane matrix.

Preferably, in the step (1), the polymer includes any one of polyvinylidene fluoride, polyethersulfone, cellulose acetate and polyamide, preferably polyvinylidene fluoride.

Preferably, in step (1), the mass ratio of the polymer to the porogen is 50-80:1, such as 52:1, 53:1, 54:1, 55:1, 56:1, 57:1, 58:1, 59:1, 60:1, 61:1, 62:1, 65:1, 70:1, 74:1, 78:1, 79:1, etc., preferably 60: 1.

Preferably, in step (1), every 1g of the pore-forming agent is dissolved in 500mL of 300-mL solvent, such as 320mL, 330mL, 350mL, 370mL, 380mL, 390mL, 400mL, 410mL, 420mL, 430mL, 440mL, 450mL, 460mL, 470mL, 480mL, 490mL, etc., preferably 400 mL.

Preferably, in step (1), the pore-forming agent comprises polyvinylpyrrolidone.

Preferably, in step (1), the solvent comprises N, N-dimethylacetamide.

Preferably, in step (1), the primary stirring is carried out at 20 to 30 ℃, for example, 21 ℃, 22 ℃, 23 ℃, 24 ℃, 25 ℃, 26 ℃, 27 ℃, 28 ℃, 29 ℃ and the like, preferably 27 ℃.

Preferably, in the step (1), the rate of the primary stirring is 400-500 rpm.

Preferably, in step (1), the polymer is slowly added to the porogen solution.

Preferably, in the step (1), the rate of the secondary stirring is 400-500 rpm.

Preferably, in step (1), the mixed dope solution is stored for 24 hours to remove air bubbles before the coating of the mixed dope solution.

Preferably, in the step (1), the mixed casting solution is coated on the glass substrate using a 200 μm thick doctor blade.

Preferably, in the step (1), the peeling method comprises peeling with warm water.

Preferably, the step (1) specifically comprises the following steps: dissolving 1 part by weight of polyvinylpyrrolidone in N, N-dimethylacetamide, carrying out primary stirring at the temperature of 20-30 ℃ at the speed of 400-500rpm to obtain a pore-forming agent solution, adding 50-80 parts by weight of polyvinylidene fluoride into the pore-forming agent solution, carrying out secondary stirring at the speed of 400-500rpm to obtain a mixed casting solution, storing the mixed casting solution for 24 hours to remove air bubbles, then coating the mixed casting solution on a glass plate by using a scraper with the thickness of 200 mu m, and stripping by using warm water to obtain a porous polymer membrane matrix.

Preferably, in step (2), the polymerization reaction is a gas phase polymerization reaction.

Preferably, in step (2), the gas phase polymerization is carried out at a temperature of 12 to 25 ℃, for example, 13 ℃, 14 ℃, 15 ℃, 16 ℃, 17 ℃, 18 ℃, 19 ℃, 20 ℃, 21 ℃, 22 ℃, 23 ℃, 24 ℃ and the like, preferably 15 ℃.

Preferably, in step (2), the gas phase polymerization time is 2 to 8 hours, such as 2.3 hours, 3.2 hours, 3.3 hours, 3.4 hours, 3.5 hours, 3.6 hours, 3.7 hours, 3.8 hours, 3.9 hours, 4 hours, 4.1 hours, 4.2 hours, 4.3 hours, 4.4 hours, 4.5 hours, 4.6 hours, 4.7 hours, 4.8 hours, 4.9 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours and the like, preferably 4 hours.

Preferably, in step (2), the gas-phase polymerization is carried out in a vacuum drier.

Preferably, in the step (2), the vacuum degree of the vacuum dryer is 0.09-0.1 MPa.

Preferably, in step (2), the molar ratio of bulky anion salt to pyrrole is from 0.005 to 0.01:1, preferably 0.007: 1.

Preferably, in the step (2), the mixed solution of the bulky anion salt and the pyrrole is formed by mixing the pyrrole and the bulky anion salt solution.

Preferably, the concentration of the bulky anionic salt solution is 0.05 to 0.2mol/L, such as 0.08mol/L, 0.1mol/L, 0.12mol/L, 0.14mol/L, 0.16mol/L, 0.18mol/L, etc., preferably 0.1 mol/L;

preferably, in step (2), the alkylbenzene sulfonate comprises sodium dodecylbenzene sulfonate.

Preferably, in step (2), the alkyl sulfonate comprises sodium dodecyl sulfate.

Preferably, in step (2), the alkyl sulfate salt comprises sodium lauryl sulfate.

Preferably, in step (2), the bulky anion salt comprises an alkylbenzene sulfonate.

Preferably, the porous polymer membrane matrix obtained in step (1) is soaked in FeCl before step (2)₃In ethanol solution.

Preferably, the FeCl₃FeCl in ethanol solution₃The concentration of (b) is 50-100g/L, for example 52g/L, 55g/L, 58g/L, 60g/L, 70g/L, 80g/L, 90g/L, etc., preferably 50 g/L.

Preferably, the FeCl₃The volume of the ethanol solution is 20 to 50mL, for example, 22mL, 23mL, 25mL, 30mL, 35mL, 40mL, 45mL, etc., preferably 30 mL.

Preferably, the porous polymer membrane substrate is soaked in FeCl₃Ethanol solutionThe time in (1) is 3-10min, such as 4min, 5min, 6min, 7min, 8min, 9min, etc., preferably 5 min.

Preferably, the step (2) specifically comprises soaking the porous polyvinylidene fluoride membrane substrate obtained in the step (1) in 20-50mL of FeCl with the concentration of 50-100g/L₃Putting a porous polyvinylidene fluoride membrane matrix into a mixed solution formed by mixing pyrrole and a bulky anion salt solution with the concentration of 0.05-0.2mol/L after drying in the air for 3-10min, wherein the molar ratio of the bulky anion salt to the pyrrole is 0.005-0.01:1, then carrying out gas phase polymerization in a vacuum drier at 12-25 ℃ for 2-8h to form a polypyrrole membrane, and cleaning by using the mixed solution of ethanol and deionized water to obtain the electric response polymer membrane.

Preferably, the preparation method comprises the following steps:

(1) dissolving 1 part by weight of polyvinylpyrrolidone in N, N-dimethylacetamide, carrying out primary stirring at the temperature of 20-30 ℃ at the speed of 400-500rpm to obtain a pore-forming agent solution, adding 50-80 parts by weight of polyvinylidene fluoride into the pore-forming agent solution, carrying out secondary stirring at the speed of 400-500rpm to obtain a mixed casting solution, storing the mixed casting solution for 24 hours to remove air bubbles, then coating the mixed casting solution on a glass plate by using a scraper with the thickness of 200 mu m, and stripping by using warm water to obtain a porous polymer membrane substrate;

(2) soaking the porous polyvinylidene fluoride membrane substrate obtained in the step (1) in 20-50mL of FeCl with the concentration of 50-100g/L₃Putting a porous polyvinylidene fluoride membrane matrix into a mixed solution formed by mixing pyrrole and a bulky anion salt solution with the concentration of 0.05-0.2mol/L after drying in the air for 3-10min, wherein the molar ratio of the bulky anion salt to the pyrrole is 0.005-0.01:1, then carrying out gas phase polymerization in a vacuum drier at 12-25 ℃ for 2-8h to form a polypyrrole membrane, and cleaning by using the mixed solution of ethanol and deionized water to obtain the electric response polymer membrane.

It is a further object of the present invention to provide a method of using an electrically responsive polymer film according to one of the objects, said method of using comprising method (a) and/or method (b);

the method (a) comprises: in deionized water, applying oxidation potential to the polluted electric response polymer membrane to enlarge the aperture of the electric response polymer membrane, and performing backwashing;

the method (b) comprises: in the solution containing the electrolyte, a reduction potential is applied to the electric response polymer membrane to reduce the pore diameter of the electric response polymer membrane, and selective interception is realized.

Preferably, the solvent for the back washing is deionized water.

Preferably, the pore size of the electrically responsive polymer membrane in process (a) is enlarged to 70-82nm, such as 71nm, 72nm, 73nm, 74nm, 75nm, 76nm, 77nm, 78nm, 79nm, 80nm, 81nm, etc., preferably 82 nm.

Preferably, the pore size of the electrically responsive polymer membrane in method (b) is reduced to 65-75nm, such as 66nm, 67nm, 68nm, 69nm, 70nm, 71nm, 72nm, 73nm, 74nm, etc., preferably 70 nm.

Preferably, the electrolyte comprises any one or a combination of at least two of sodium chloride, potassium chloride and sodium sulfate.

The fourth object of the present invention is to provide the use of the electrically responsive polymer membrane according to one of the objects for water treatment.

Compared with the prior art, the invention has the following beneficial effects:

the electric response polymer membrane provided by the invention utilizes the electric effect of ion embedding/de-embedding, dynamically regulates and controls the aperture size of the response polymer membrane through the electrode potential, can effectively remove membrane pollution and realize selective interception of macromolecular organic pollutants, and has good mechanical property and stability.

After an oxidation potential is applied to the electric response polymer film and back washing is carried out, the film flux is improved by 18.19-28.97%; after the reduction potential is applied, the peak value reduction of the high molecular weight HA is 21.18-35.88%, the tensile strength of the film is 1.3-2MPa, and the stabilization time is 900 min.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

This example provides an electrically responsive polymer film, which is prepared as follows:

(1) dissolving 0.05g of polyvinylpyrrolidone in 20mL of N, N-dimethylacetamide, stirring at the speed of 450rpm at the temperature of 27 ℃ for the first time to obtain a pore-forming agent solution, adding 3g of polyvinylidene fluoride into the pore-forming agent solution, stirring at the speed of 450rpm for the second time to obtain a mixed casting solution, storing the mixed casting solution for 24 hours to remove air bubbles, then coating the mixed casting solution on a glass plate by using a scraper with the thickness of 200 mu m, and stripping by using warm water to obtain a porous polymer film matrix (the thickness is 200 mu m);

(2) soaking the porous polyvinylidene fluoride membrane substrate obtained in the step (1) in 30mL of FeCl with the concentration of 50g/L₃The preparation method comprises the following steps of drying in ethanol solution for 5min in the air, placing a porous polyvinylidene fluoride membrane substrate in a mixed solution formed by mixing 0.1mL of pyrrole and 0.1mL of sodium dodecyl benzene sulfonate solution with the concentration of 0.1mol/L (the molar ratio of the sodium dodecyl benzene sulfonate to the pyrrole is 0.007:1), then carrying out gas phase polymerization in a vacuum drier (the vacuum degree is 0.1MPa) at 15 ℃ for 4h, depositing on the substrate to form a polypyrrole membrane (the thickness is 5% of the thickness of the porous polymer membrane substrate), and cleaning with the mixed solution of ethanol and deionized water to obtain the electric response polymer membrane.

Example 2

The difference from example 1 is that in step (2), the amount of pyrrole added was 0.5mL, the amount of sodium dodecylbenzenesulfonate solution added was 0.5mL, and the thickness of the resulting polypyrrole film was 8% of the thickness of the porous polymer film substrate.

Example 3

The difference from example 1 is that in step (2), the amount of pyrrole added was 1.5mL, the amount of sodium dodecylbenzenesulfonate solution added was 1.5mL, and the thickness of the resulting polypyrrole film was 10% of the thickness of the porous polymer film substrate.

Example 4

The difference from example 1 is that in step (2), the amount of pyrrole added was 0.05mL, the amount of sodium dodecylbenzenesulfonate solution added was 0.3mL, and the thickness of the resulting polypyrrole film was 3% of the thickness of the porous polymer film substrate.

Example 5

The difference from example 1 is that in step (2), the amount of pyrrole added was 1.8mL, the amount of sodium dodecylbenzenesulfonate solution added was 1.8mL, and the thickness of the resulting polypyrrole film was 12% of the thickness of the porous polymer film substrate.

Example 6

The difference from example 1 is that the sodium dodecylbenzenesulfonate solution is added in an amount of 0.07mL, and the molar ratio of sodium dodecylbenzenesulfonate to pyrrole is 0.005: 1.

Example 7

The difference from example 1 is that the sodium dodecylbenzenesulfonate solution is added in an amount of 0.14mL, and the molar ratio of sodium dodecylbenzenesulfonate to pyrrole is 0.01: 1.

Example 8

The difference from example 1 is that the sodium dodecylbenzenesulfonate solution is added in an amount of 0.056mL and the molar ratio of sodium dodecylbenzenesulfonate to pyrrole is 0.004: 1.

Example 9

The difference from example 1 is that the sodium dodecylbenzenesulfonate solution is added in an amount of 0.21mL, and the molar ratio of sodium dodecylbenzenesulfonate to pyrrole is 0.015: 1.

Example 10

The difference from example 1 is that in step (2), the temperature of the gas phase polymerization was 12 ℃.

Example 11

The difference from example 1 is that in step (2), the temperature of the gas phase polymerization was 25 ℃.

Example 12

The difference from example 1 is that in step (2), the temperature of the gas phase polymerization was 30 ℃.

Example 13

The difference from example 1 is that in step (2), the time for gas phase polymerization was 2 hours.

Example 14

The difference from example 1 is that in step (2), the time for the gas-phase polymerization was 8 hours.

Example 15

The difference from example 1 is that in step (2), the time for gas phase polymerization was 1 hour.

Example 16

The difference from example 1 is that step (2) comprises the steps of:

soaking the porous polyvinylidene fluoride membrane substrate obtained in the step (1) in 30mL of FeCl with the concentration of 50g/L₃Putting the porous polyvinylidene fluoride membrane substrate in a mixed solution formed by mixing 0.1mL of pyrrole and 0.1mL of sodium dodecyl benzene sulfonate solution with the concentration of 0.1mol/L (the molar ratio of the sodium dodecyl benzene sulfonate to the pyrrole is 0.007:1) after drying in the air, reacting for 4 hours at 15 ℃ to form a polypyrrole membrane (the thickness is 5% of the thickness of the porous polymer membrane substrate), and cleaning by using the mixed solution of ethanol and deionized water to obtain the electric response polymer membrane.

Example 17

(1) Dissolving 0.05g of polyvinylpyrrolidone in 15mL of N, N-dimethylacetamide, stirring at the speed of 500rpm at the temperature of 20 ℃ for the first time to obtain a pore-forming agent solution, adding 2.5g of polyvinylidene fluoride into the pore-forming agent solution, stirring at the speed of 400rpm for the second time to obtain a mixed casting solution, storing the mixed casting solution for 24 hours to remove air bubbles, then coating the mixed casting solution on a glass plate by using a scraper with the thickness of 200 mu m, and stripping by using warm water to obtain a porous polymer membrane matrix (the thickness is 200 mu m);

(2) soaking the porous polyvinylidene fluoride membrane substrate obtained in the step (1) in 20mL of FeCl with the concentration of 50g/L₃Drying in ethanol solution for 3min, placing porous polyvinylidene fluoride membrane substrate in mixed solution of 0.1mL pyrrole and 0.2mL dioctyl sodium sulfonate solution with concentration of 0.05mol/L (molar ratio of dioctyl sodium sulfonate and pyrrole is 0.007:1), performing gas phase polymerization in vacuum drier (vacuum degree of 0.09MPa) at 15 deg.C for 4 hr, and depositing on the substrate to form polypyrrole membrane (with thickness of porous polypyrrole)8% of the thickness of the polymer film substrate), and the electric response polymer film is obtained after cleaning by using a mixed solution of ethanol and deionized water.

Example 18

(1) Dissolving 0.05g of polyvinylpyrrolidone in 25mL of N, N-dimethylacetamide, stirring at the speed of 400rpm at the temperature of 30 ℃ for the first time to obtain a pore-forming agent solution, adding 4g of polyvinylidene fluoride into the pore-forming agent solution, stirring at the speed of 500rpm for the second time to obtain a mixed casting solution, storing the mixed casting solution for 24 hours to remove air bubbles, then coating the mixed casting solution on a glass plate by using a scraper with the thickness of 200 mu m, and stripping by using warm water to obtain a porous polymer film matrix (the thickness is 200 mu m);

(2) soaking the porous polyvinylidene fluoride membrane substrate obtained in the step (1) in 50mL of FeCl with the concentration of 100g/L₃The preparation method comprises the following steps of drying in ethanol solution for 10min in the air, placing a porous polyvinylidene fluoride membrane substrate in a mixed solution formed by mixing 0.1mL of pyrrole and 0.05mL of sodium dodecyl sulfate solution with the concentration of 0.2mol/L (the molar ratio of the sodium dodecyl sulfate to the pyrrole is 0.007:1), carrying out gas phase polymerization in a vacuum drier (the vacuum degree is 0.1MPa) at 15 ℃ for 4h, depositing the substrate to form a polypyrrole membrane (the thickness is 5% of the thickness of the porous polymer membrane substrate), and cleaning the polypyrrole membrane by using the mixed solution of ethanol and deionized water to obtain the electric response polymer membrane.

Example 19

The difference from example 1 is that in step (2), the sodium dodecylbenzenesulfonate solution is replaced with an equal concentration and amount of sodium dodecylsulfate solution.

Comparative example 1

The difference from example 1 is that in step (2), no sodium dodecylbenzenesulfonate solution is added.

Comparative example 2

The difference from example 1 is that in step (2), the sodium dodecylbenzenesulfonate solution is replaced with sodium p-toluenesulfonate in an equal concentration and amount.

Performance testing

The following performance tests were performed on the electric responsive polymer films in examples and comparative examples:

(1) back flushing

Preparing 20mg/L Humic Acid (HA) solution, filtering by using a cross-flow filtering device, applying an oxidation potential for 10min in situ by taking an electric response polymer membrane as an anode after 1h of pollution, then back flushing for 1h by using deionized water, and calculating and recording the membrane flux increase (%) compared with that without applying a potential.

(2) Selective interception

Preparing 20mg/L Humic Acid (HA) solution containing 0.1mol/L NaCl as electrolyte, filtering by using a cross-flow filtering device, applying a reduction potential on an electric response polymer membrane for 10 minutes, and calculating and recording the peak reduction (%) of HA with the molecular weight of 10-15KDa in the leachate after reduction.

The cross-flow filtration device described above contained the electrically responsive polymer membranes obtained in examples and comparative examples, and repeated tests were performed on filtration devices containing different membranes, with the results shown in table 1.

(3) Mechanical Property test

The tensile strength of the film was measured using an electronic universal tester, and the cut film (30 mm. times.5 mm. times.10 μm (length. times. width. times. thickness)) was held by a fixed and movable grip at a distance of 10 mm. The static load was set at 1N and the displacement rate was 2 mm/min.

(4) Stability test

The procedure of performance test (1) was repeated until the membrane was damaged (significant membrane flux increase occurred) and the working time (min) at this time was recorded to characterize the stability of the electrically responsive polymer membrane.

TABLE 1

As can be seen from Table 1, the electric response polymer membrane provided by the invention can dynamically regulate and control the pore size of the response polymer membrane through the electrode potential, can effectively remove membrane pollution and realize selective interception of macromolecular organic pollutants, and has good mechanical properties and stability. The membrane flux is improved by 18.19 to 28.97 percent after backwashing; after the reduction potential is applied, the peak value reduction of the high molecular weight HA is 21.18-35.88%, the tensile strength of the film is 1.3-2MPa, and the stabilization time is 900 min.

The polypyrrole film in the electric response polymer film provided by the comparative example 1 is not doped with large-volume anions, and after back washing, the film flux is only improved by 5.63%; the peak reduction of the high molecular weight HA after the reduction potential was applied was only 8.06%, which failed to achieve dynamic control of the pore size of the polymer membrane and also deteriorated mechanical properties and stability.

In the comparative example 2, the polypyrrole film is doped with small-volume anions, and after back washing, the film flux is only improved by 6.31%; the peak reduction of the high molecular weight HA after application of the reduction potential was only 8.76%, which failed to achieve dynamic control of the pore size of the polymer membrane and also deteriorated mechanical properties and stability.

Therefore, the polypyrrole film is doped with large-volume anions, so that the conductivity of the polypyrrole film is improved, and the dynamic regulation and control of the electric response polymer film as well as excellent mechanical properties and stability are realized.

It can be seen from comparative examples 1-4 that when the thickness of the polypyrrole film is 5-10% of the porous polymer film matrix (examples 1-3), the obtained electrically responsive polymer film has better conductivity, better back washing and selective interception effects, and optimal mechanical properties and stability.

It can be seen from comparison of examples 1 and 6-9 that when the molar doping ratio of the alkylbenzene sulfonate ions is 0.005-0.01:1 (examples 1, 6 and 7), the obtained electrically responsive polymer membrane has better conductivity and better back washing and selective interception effects.

As is clear from comparison of examples 1 and 10 to 15, when the temperature of the gas phase polymerization reaction is 12 to 25 ℃ and the time is 2 to 8 hours (examples 1, 10 to 11 and 13 to 14), the conductivity of the obtained electro-responsive polymer membrane can be further improved, thereby improving the back washing and selective interception effects thereof, and when the reaction temperature is too high (example 12) or the reaction time is too short (example 15), the effects are deteriorated.

It can be seen from comparison of examples 1 and 16 that the electrically responsive polymer membrane obtained by gas phase polymerization (example 1) has better back-washing and selective interception effects than the electrically responsive polymer membrane obtained by liquid phase polymerization (example 16).

Comparing example 1 and example 19, it can be seen that when doping alkyl benzene sulfonate ions (example 1), the conductivity of the point-responsive polymer film can be further improved compared to doping alkyl sulfate ions (example 19), thereby improving the backwash film flux and the peak reduction of high molecular weight HA.

The present invention is illustrated in detail by the examples described above, but the present invention is not limited to the details described above, i.e., it is not intended that the present invention be implemented by relying on the details described above. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims

1. An electric response polymer water treatment membrane is characterized by comprising a porous polymer membrane matrix and a polypyrrole membrane covering the pore wall and the surface of the porous polymer membrane matrix, wherein the polypyrrole membrane is doped with bulky anions, and the thickness of the polypyrrole membrane accounts for 5-10% of that of the porous polymer membrane matrix; the polypyrrole is polymerized by pyrrole, and the molar ratio of the bulky anion to the pyrrole is 0.005-0.01: 1;

the alkyl is C7-C12 alkyl;

the polypyrrole is prepared by gas-phase polymerization of pyrrole;

the temperature of the gas-phase polymerization is 12-25 ℃, and the time of the gas-phase polymerization is 2-8 h.

2. The electrically responsive polymer water treatment membrane as claimed in claim 1, wherein the thickness of said porous polymer membrane substrate is 200-400 μm.

3. An electrically responsive polymeric water treatment membrane as claimed in claim 1, wherein the porous polymeric membrane substrate has a thickness of 200 μm.

4. An electro-responsive polymeric water treatment membrane as claimed in claim 1, wherein the polymer in the porous polymeric membrane matrix comprises any one of polyvinylidene fluoride, polyethersulfone, cellulose acetate and polyamide.

5. An electrically responsive polymeric water treatment membrane as claimed in claim 1, wherein the polymer in the porous polymeric membrane matrix comprises polyvinylidene fluoride.

6. The electrically responsive polymeric water treatment membrane according to claim 1, wherein said polypyrrole is polymerized from pyrrole in a molar ratio of bulky anion to pyrrole of 0.007: 1.

7. The electrically responsive polymeric water treatment membrane according to claim 1, wherein the temperature of said gas phase polymerization is 15 ℃.

8. The electrically responsive polymeric water treatment membrane according to claim 1, wherein said gas phase polymerization is for a period of 4 h.

9. The electrically responsive polymeric water treatment membrane according to claim 1, wherein said alkylbenzene sulfonate ion is dodecylbenzene sulfonate ion.

10. An electrically responsive polymeric water treatment membrane as claimed in claim 1, wherein said alkyl sulphate ions are dodecyl sulphate ions.

11. The electrically responsive polymeric water treatment membrane according to claim 1, wherein said alkyl sulfonate ions are dodecyl sulfonate ions.

12. The electrically responsive polymeric water treatment membrane according to claim 1, wherein said bulky anion comprises alkylbenzene sulfonate ions.

13. The electrically responsive polymer water treatment membrane as claimed in claim 1, wherein an average pore diameter of the electrically responsive polymer water treatment membrane when an oxidation potential is applied is 70-82 nm.

14. The electrically responsive polymer water treatment membrane as claimed in claim 1, wherein an average pore diameter of the electrically responsive polymer water treatment membrane when an oxidation potential is applied is 82 nm.

15. The electrically responsive polymer water treatment membrane as claimed in claim 1, wherein an average pore diameter of the electrically responsive polymer water treatment membrane when a reduction potential is applied is 65 to 75 nm.

16. The electrically responsive polymer water treatment membrane as claimed in claim 1, wherein an average pore diameter of the electrically responsive polymer water treatment membrane when a reduction potential is applied is 70 nm.

17. A method of preparing an electrically responsive polymeric water treatment membrane according to any one of claims 1 to 16, comprising the steps of:

(2) placing the porous polymer film matrix in a mixed solution of bulky anion salt and pyrrole, and forming a polypyrrole film doped with bulky anions on the pore wall and the surface of the porous polymer film matrix through polymerization reaction to obtain the electric response polymer water treatment film;

the bulky anion salt comprises any one or at least two of alkyl benzene sulfonate, alkyl sulfate and dioctyl dibutyrate sulfonate;

the alkyl is C7-C12 alkyl;

in the step (2), the molar ratio of the bulky anion salt to the pyrrole is 0.005-0.01: 1;

in the step (2), the polymerization reaction is a gas-phase polymerization reaction;

in the step (2), the temperature of the gas-phase polymerization is 12-25 ℃;

in the step (2), the time of the gas-phase polymerization is 2-8 h.

18. The method according to claim 17, wherein the step (1) specifically comprises: dissolving a pore-forming agent in a solvent, stirring for the first time to obtain a pore-forming agent solution, adding a polymer into the pore-forming agent solution, stirring for the second time to obtain a mixed membrane casting solution, coating the mixed membrane casting solution on a glass plate, and stripping to obtain a porous polymer membrane matrix.

19. The method according to claim 17, wherein in the step (1), the polymer includes any one of polyvinylidene fluoride, polyethersulfone, cellulose acetate and polyamide.

20. The method according to claim 17, wherein in the step (1), the polymer comprises polyvinylidene fluoride.

21. The production method according to claim 18, wherein in step (1), the mass ratio of the polymer to the pore-forming agent is 50-80: 1.

22. The production method according to claim 18, wherein in step (1), the mass ratio of the polymer to the pore-forming agent is 60: 1.

23. The method as claimed in claim 18, wherein in the step (1), the pore-forming agent is dissolved in 500mL of the solvent per 1g of the pore-forming agent.

24. The method according to claim 18, wherein in the step (1), the pore-forming agent is dissolved in 400mL of the solvent per 1g of the pore-forming agent.

25. The method according to claim 18, wherein in the step (1), the pore-forming agent comprises polyvinylpyrrolidone.

26. The method according to claim 18, wherein in the step (1), the solvent comprises N, N-dimethylacetamide.

27. The production method according to claim 18, wherein in the step (1), the primary stirring is performed at 20 to 30 ℃.

28. The production method according to claim 18, wherein in the step (1), the primary stirring is performed at 27 ℃.

29. The method as claimed in claim 18, wherein in the step (1), the primary stirring rate is 400-500 rpm.

30. The method of claim 18, wherein in step (1), the polymer is slowly added to the porogen solution.

31. The method as claimed in claim 18, wherein the second stirring speed in step (1) is 400-500 rpm.

32. The production method according to claim 18, characterized in that, in step (1), the mixed dope solution is stored for 24 hours to remove air bubbles before the application of the mixed dope solution.

33. The production method according to claim 18, wherein, in the step (1), the mixed dope solution is coated on the glass substrate using a 200 μm thick doctor blade.

34. The method according to claim 18, wherein in the step (1), the peeling method comprises peeling with warm water.

35. The method according to claim 18, wherein the step (1) comprises the steps of: dissolving 1 part by weight of polyvinylpyrrolidone in N, N-dimethylacetamide, carrying out primary stirring at the temperature of 20-30 ℃ at the speed of 400-500rpm to obtain a pore-forming agent solution, adding 50-80 parts by weight of polyvinylidene fluoride into the pore-forming agent solution, carrying out secondary stirring at the speed of 400-500rpm to obtain a mixed casting solution, storing the mixed casting solution for 24 hours to remove air bubbles, then coating the mixed casting solution on a glass plate by using a scraper with the thickness of 200 mu m, and stripping by using warm water to obtain a porous polymer membrane matrix.

36. The production method according to claim 17, wherein the temperature of the gas-phase polymerization in the step (2) is 15 ℃.

37. The production method according to claim 17, wherein the gas-phase polymerization is carried out for 4 hours in the step (2).

38. The production method according to claim 17, wherein in the step (2), the gas-phase polymerization is carried out in a vacuum drier.

39. The production method according to claim 38, wherein in the step (2), the vacuum degree of the vacuum dryer is 0.09 to 0.1 MPa.

40. The method of claim 17, wherein in step (2), the molar ratio of the bulky anion salt to pyrrole is 0.007: 1.

41. The method according to claim 17, wherein in the step (2), the mixed solution of the bulky anion salt and the pyrrole is prepared by mixing the pyrrole and the bulky anion salt solution.

42. The method of claim 41, wherein the concentration of the bulk anionic salt solution is 0.05 to 0.2 mol/L.

43. The method of claim 41, wherein the concentration of the bulky anionic salt solution is 0.1 mol/L.

44. The method according to claim 17, wherein in the step (2), the alkylbenzene sulfonate comprises sodium dodecylbenzenesulfonate.

45. The method according to claim 17, wherein in the step (2), the alkylsulfonate includes sodium dodecylsulfonate.

46. The method according to claim 17, wherein in the step (2), the alkyl sulfate includes sodium lauryl sulfate.

47. The method of claim 17, wherein in step (2), the bulky anion salt comprises an alkylbenzene sulfonate.

48. The method according to claim 17, wherein the porous polymer obtained in step (1) is subjected to a step (2) before the step (1)Immersing the film-coated substrate in FeCl₃In ethanol solution.

49. The method of claim 48, wherein the FeCl is₃FeCl in ethanol solution₃The concentration of (A) is 50-100 g/L.

50. The method of claim 48, wherein the FeCl is₃FeCl in ethanol solution₃The concentration of (2) is 50 g/L.

51. The method of claim 48, wherein the FeCl is₃The volume of the ethanol solution is 20-50 mL.

52. The method of claim 48, wherein the FeCl is₃The volume of the ethanol solution was 30 mL.

53. The method of claim 48, wherein the porous polymeric membrane substrate is soaked in FeCl₃The time in the ethanol solution is 3-10 min.

54. The method of claim 48, wherein the porous polymeric membrane substrate is soaked in FeCl₃The time in ethanol solution was 5 min.

55. The method according to claim 17, wherein the step (2) specifically comprises: soaking the porous polyvinylidene fluoride membrane substrate obtained in the step (1) in 20-50mL of FeCl with the concentration of 50-100g/L₃Drying in ethanol solution for 3-10min, placing porous polyvinylidene fluoride membrane matrix in mixed solution of pyrrole and 0.05-0.2mol/L bulky anion salt solution at molar ratio of 0.005-0.01:1, gas-phase polymerizing at 12-25 deg.C for 2-8 hr to form polypyrrole membrane, and removing ions with ethanol and deionized waterAnd cleaning the water mixed solution to obtain the electric response polymer water treatment membrane.

56. The method of manufacturing according to claim 17, comprising the steps of:

(2) soaking the porous polyvinylidene fluoride membrane substrate obtained in the step (1) in 20-50mL of FeCl with the concentration of 50-100g/L₃Putting a porous polyvinylidene fluoride membrane matrix into a mixed solution formed by mixing pyrrole and a bulky anion salt solution with the concentration of 0.05-0.2mol/L after drying in the air for 3-10min, wherein the molar ratio of the bulky anion salt to the pyrrole is 0.005-0.01:1, then carrying out gas phase polymerization in a vacuum drier at 12-25 ℃ for 2-8h to form a polypyrrole membrane, and cleaning by using the mixed solution of ethanol and deionized water to obtain the electrically-responsive polymer water treatment membrane.

57. A method of using an electrically responsive polymeric water treatment membrane according to any one of claims 1 to 16, wherein the method of use comprises method (a) and/or method (b);

the method (a) comprises: in deionized water, applying oxidation potential to the polluted electric response polymer water treatment membrane to enlarge the aperture of the electric response polymer water treatment membrane, and performing backwashing;

the method (b) comprises: in the solution containing electrolyte, reducing potential is applied to the electric response polymer water treatment membrane to reduce the pore diameter of the electric response polymer water treatment membrane, and selective interception is realized.

58. The use of claim 57, wherein the backflushed solvent is deionized water.

59. The use of the electrically responsive polymeric water treatment membrane according to claim 57, wherein in method (a) the pore size of the membrane is enlarged to 70-82 nm.

60. The use of the electrically responsive polymer water treatment membrane according to claim 57, wherein in method (a) the pore size of the membrane is enlarged to 82 nm.

61. The use of the electrically responsive polymeric water treatment membrane as claimed in claim 57, wherein in method (b) the pore size of the membrane is reduced to 65-75 nm.

62. The use of the electrically responsive polymeric water treatment membrane of claim 57 wherein in method (b) the pore size of the membrane is reduced to 70 nm.

63. Use of an electrically responsive polymeric water treatment membrane according to any of claims 1 to 16 for water treatment.